Liquid crystal displays are widening the usage year by year as image display apparatus requiring low consumption of electric power and a small space. Having large viewing angle dependency of images is a big defect of liquid crystal displays, however, liquid crystal modes such as VA mode and IPS mode having high angle of visibility have been put to practical use in recent years. As a result, the demand for liquid crystal displays is rapidly spreading also on the market requiring high angle of visibility such as televisions.
With such a tendency, optical compensating films for use in liquid crystal displays are required to exhibit a broader range of retardation. A method of making a cellulose acylate film exhibit retardation to thereby impart the cellulose acylate film two functions of the protective film and the retardation film of a polarizing plate at the same time can greatly simplify the producing process of a polarizing plate with an optical compensation function, so that many methods have been investigated.
For imparting retardation to a cellulose acylate film, a method of using cellulose acylate having a low degree of acylation, and a method of the addition of a compound having a specific shape are known. The latter method is especially advantageous in that retardation can be controlled merely by the addition amount of an additive, so that various films different in retardations can be easily produced at will, and a method of using a disc-like compound is disclosed in JP-A-2003-344655 (The term “JP-A” as used herein refers to an “unexamined published Japanese patent application”.), and a method of using a rod-like compound is disclosed in JP-A-2002-363343.